U.S. patent number 5,743,685 [Application Number 08/252,849] was granted by the patent office on 1998-04-28 for clamping device for a workpiece processing machine.
This patent grant is currently assigned to Quickmill, Inc.. Invention is credited to David C. Piggott.
United States Patent |
5,743,685 |
Piggott |
April 28, 1998 |
Clamping device for a workpiece processing machine
Abstract
Disclosed herein is a clamping device comprising a
workpiece-engaging portion including a workpiece-engaging surface;
sealing means for sealing the workpiece-engaging portion with the
workpiece; the sealing means including a first resilient member
arranged to seal between the workpiece-engaging surface and the
workpiece, wherein the sealing means, the workpiece-engaging
portion and the workpiece collectively form a first chamber; vacuum
supply means for supplying a vacuum to the first chamber to draw
together the workpiece and the workpiece-engaging portion; and
pressure supply means for applying a pressure to the first
resilient member to force the first resilient member against the
workpiece-engaging portion and the workpiece. Also disclosed is a
method for clamping a workpiece to a processing machine as well as
a workpiece processing machine incorporating the clamping
device.
Inventors: |
Piggott; David C. (Lakefield,
CA) |
Assignee: |
Quickmill, Inc.
(CA)
|
Family
ID: |
22957812 |
Appl.
No.: |
08/252,849 |
Filed: |
June 2, 1994 |
Current U.S.
Class: |
409/131; 269/21;
279/3; 408/76; 409/225; 409/903 |
Current CPC
Class: |
B25B
11/005 (20130101); Y10T 409/303752 (20150115); Y10T
408/554 (20150115); Y10T 409/309016 (20150115); Y10T
279/11 (20150115); Y10S 409/903 (20130101) |
Current International
Class: |
B25B
11/00 (20060101); B23Q 003/00 () |
Field of
Search: |
;409/131,225,903 ;269/21
;279/3 ;408/76,1R |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Howell; Daniel W.
Attorney, Agent or Firm: O'Rourke; Thomas A.
Claims
I claim:
1. A clamping device for a workpiece processing machine
comprising;
a workpiece-engaging portion including a workpiece-engaging
surface;
sealing means for sealing said workpiece-engaging portion with said
workpiece; said sealing means including a first resilient member
arranged to seal between said workpiece-engaging surface and said
workpiece, wherein said sealing means, said workpiece-engaging
portion and said workpiece collectively form a first chamber;
vacuum supply means or supplying a vacuum to said first chamber to
draw together said workpiece and said workpiece-engaging
portion;
said workpiece engaging portion further comprising a recess having
an inner surface portion, said first resilient member being
positioned in said recess and having an exposed surface which is
exposed to said inner surface portion, said first resilient member
being movable in said recess to cause said exposed surface to be
spaced from said inner surface portion to form a second chamber
therebetween, and
pressure supply means for pressurizing said second chamber, thereby
to force said first resilient member against said workpiece,
wherein said first resilient member is movable under the action of
said pressure to establish a seal between said workpiece and said
first resilient member, while maintaining a seal between said first
resilient member and said recess.
2. A device as defined in claim 1 wherein said exposed surface
includes an outer surface on said resilient member.
3. A clamping device for a workpiece processing machine
comprising;
a workpiece-engaging portion including a workpiece-engaging
surface;
sealing means for sealing said workpiece-engaging portion with said
workpiece; said sealing means including a first resilient member
arranged to seal between said workpiece-engaging surface and said
workpiece, wherein said sealing means, said workpiece-engaging
portion and said workpiece collectively form a first chamber; said
first resilient member being an o-ring;
vacuum supply means for supplying a vacuum to said first chamber to
draw together said workpiece and said workpiece-engaging portion;
and
pressure supply means for applying a pressure to said first
resilient member to force said first resilient member against said
workpiece-engaging portion and said workpiece.
4. A device as defined in claim 1 wherein said machine further
comprises a bed and said workpiece-engaging portion includes a
sandwich member positioned on said bed.
5. A clamping device for a workpiece processing machine of the type
having a bed, said clamping device comprising;
a workpiece-engaging portion including a workpiece-engaging
surface; said workpiece-engaging portion further including a
sandwich member positioned on said bed;
sealing means for sealing said workpiece-engaging portion with said
workpiece; said sealing means including a first resilient member
arranged to seal between said workpiece-engaging surface and said
workpiece, wherein said sealing means said workpiece-engaging
portion and said workpiece collectively form a first chamber;
vacuum supply means for supplying a vacuum to said first chamber to
draw together said workpiece and said workpiece-engaging portion;
and
pressure supply means for applying a pressure to said first
resilient member to force said first resilient member against said
workpiece-engaging portion and said workpiece;
said sandwich member having a pair of opposite surfaces including
said workpiece-engaging surface and a bed-engaging surface, an
aperture formed in said sandwich member and extending between said
workpiece-engaging and said bed-engaging surfaces, wherein said
aperture has a periphery formed between said workpiece-engaging and
said bed-engaging surfaces;
said sealing means further comprising a second resilient member
arranged to seal between said bed-engaging surface and said bed,
wherein said sealing means, said sandwich member, said bed and said
workpiece collectively form said first chamber;
said vacuum supply means being further arranged to supply a vacuum
to said first chamber to draw together said workpiece, said
sandwich member and said bed; and
said pressure supply means being further arranged to apply a
pressure to both said first and second resilient members to force
said first resilient member against said sandwich member and said
workpiece and to force said second resilient member against said
sandwich member and said bed.
6. A device as defined in claim 5 wherein said sandwich member
further includes a first recess formed adjacent said periphery in
said workpiece-engaging surface and a second recess formed adjacent
said periphery in said bed-engaging surface, said first and second
resilient members being engaged with said first and second recesses
respectively, wherein said first and second resilient members and
said first and second recesses collectively form a second chamber,
said pressure supply means supplying pressure to said second
chamber.
7. A device as defined in claim 6 wherein said first and second
resilient members are o-rings.
8. A method for clamping a workpiece to a workpiece processing
machine, comprising the steps of:
providing a workpiece-engaging portion including a
workpiece-engaging surface;
locating a workpiece on said workpiece-engaging surface;
sealing said workpiece-engaging portion with said workpiece, said
step of sealing further including the steps of:
providing a first resilient member to seal between said
workpiece-engaging surface and said workpiece so that said
workpiece-engaging portion and said workpiece collectively form a
first chamber;
providing said workpiece engaging portion with a recess having an
inner surface portion,
positioning said first resilient member in said recess
providing said first resilient member with an exposed surface which
is exposed to said inner surface portion;
arranging said first resilient member to be movable in said recess,
thereby to form a second chamber between said exposed surface and
said inner surface portion,
providing a supply of vacuum to said first chamber to draw together
said workpiece and said workpiece-engaging portion; and
pressurizing said second chamber to force said first resilient
member outwardly against said workpiece, wherein said first
resilient member is movable in said recess under the action of said
pressure to establish an enhanced seal between said first resilient
member and said workpiece, while maintaining a seal between said
first resilient member and said recess.
9. A method as defined in claim 8 wherein said exposed surface
includes an outer surface on said resilient member.
10. A method for clamping a workpiece to a workpiece processing
machine, comprising the steps of:
providing a workpiece-engaging portion including a
workpiece-engaging surface;
locating a workpiece on said workpiece-engaging surface;
sealing said workpiece-engaging portion with said workpiece, said
step of sealing further including the step of providing a first
resilient member in the form of an o-ring to seal between said
workpiece-engaging surface and said workpiece so that said
workpiece-engaging portion and said workpiece collectively form a
first chamber;
providing a supply of vacuum to said first chamber to draw together
said workpiece and said workpiece-engaging portion;
providing a supply of pressure to said first resilient member to
force said first resilient member against said workpiece-engaging
portion and said workpiece;
providing a first recess in said workpiece-engaging surface;
engaging said first resilient member with said recess and together
to form therewith a second chamber;
said step of providing a supply of pressure further including the
step of supplying pressure to said second chamber.
11. A method as defined in claim 8 wherein said machine further
comprises a bed, wherein said step of providing a
workpiece-engaging portion includes the step of providing a
sandwich member for location on said bed.
12. A method for clamping a workpiece to a workpiece processing
machine, comprising the steps of:
providing a workpiece-engaging portion including a
workpiece-engaging surface;
locating a workpiece on said workpiece-engaging surface;
sealing said workpiece-engaging portion with said workpiece, said
step of sealing further including the step of providing a first
resilient member to seal between said workpiece-engaging surface
and said workpiece so that said workpiece-engaging portion and said
workpiece collectively form a first chamber;
providing a supply of vacuum to said first chamber to draw together
said workpiece and said workpiece-engaging portion;
providing a supply of pressure to said first resilient member to
force said first resilient member against said workpiece-engaging
portion and said workpiece;
providing a first recess in said workpiece-engaging surface;
engaging said first resilient member with said recess and together
to form therewith a second chamber;
said step of providing a supply of pressure further including the
step of supplying pressure to said second chamber;
said method further comprising the steps of:
providing a pair of opposite surfaces on said sandwich member
including a workpiece-engaging surface and a bed-engaging
surface;
forming an aperture in said sandwich member to extend between said
workpiece-engaging and said bed-engaging surfaces, wherein said
aperture has a periphery formed on both said workpiece-engaging and
said bed-engaging surfaces;
arranging said first resilient member to seal between said
workpiece-engaging surface and said workpiece,
providing a second resilient member to seal between said
bed-engaging surface and said bed, wherein said sealing means, said
sandwich member, said bed and said workpiece collectively form a
first chamber;
providing a supply of vacuum to said first chamber to draw together
said workpiece, said sandwich member and said bed; and
providing a supply of pressure to both said first and second
resilient members to force said first resilient member against said
sandwich member and said workpiece and to force said second
resilient member against said sandwich member and said bed.
13. A method as defined in claim 12 further comprising the steps
of:
providing a first recess adjacent said periphery in said
workpiece-engaging surface;
providing a second recess adjacent said periphery in said
bed-engaging surface;
engaging said first and second resilient members with said first
and second recesses respectively, wherein said first and second
resilient members and said first and second recesses collectively
form a second chamber;
said step of providing a supply of pressure further including the
step of supplying pressure to said second chamber.
14. A method as defined in claim 13 wherein said first and second
resilient members are o-rings.
15. A workpiece processing machine comprising;
a bed;
means for clamping a workpiece to said bed, including at least one
workpiece-engaging portion having a workpiece-engaging surface;
sealing means for sealing said workpiece-engaging portion with said
workpiece, said sealing means including a first resilient member
arranged to seal between said workpiece-engaging surface and said
workpiece, wherein said workpiece, said sealing means and said
workpiece-engaging portion collectively form a first chamber;
vacuum supply means for supplying a vacuum to said first chamber to
draw together said workpiece and said workpiece-engaging
portion;
said workpiece engaging portion further comprising a recess having
an inner surface portion, said first resilient member being
positioned in said recess and having an exposed surface which is
exposed to said inner surface portion, said first resilient member
being movable in said recess to cause said exposed surface to be
spaced from said inner surface portion to form a second chamber
therebetween,
pressure supply means for pressurizing said second chamber, thereby
to force said first resilient member against said workpiece,
wherein said first resilient member is movable under the action of
said pressure to establish a seal between said workpiece and said
first resilient member, while maintaining a seal between said first
resilient member and said recess.
16. A machine as defined in claim 15 wherein said exposed surface
includes an outer surface on said resilient member.
17. A workpiece processing machine comprising;
a bed;
means for clamping a workpiece to said bed, including at least one
workpiece engaging portion having a workpiece-engaging surface;
sealing means for sealing said workpiece-engaging portion with said
workpiece, said sealing means including a first resilient member
arranged to seal between said workpiece-engaging surface and said
workpiece, wherein said workpiece, said sealing means and said
workpiece-engaging portion collectively form a first chamber; said
first resilient member being an o-ring;
vacuum supply means for supplying a vacuum to said first chamber to
draw together said workpiece and said workpiece-engaging portion;
and
pressure supply means for applying a pressure to said first
resilient member to force said first resilient member against said
workpiece and said workpiece-engaging portion;
said workpiece-engaging portion further including a first recess
formed in said workpiece-engaging surface wherein said first
resilient member is engaged with said recess and together therewith
forms a second chamber, said pressure supply means supplying
pressure to said second chamber.
18. A machine as defined in claim 15 wherein said
workpiece-engaging portion includes a sandwich member mounted on
said bed.
19. A workpiece processing machine comprising;
a bed;
means for clamping a workpiece to said bed, including at least
workpiece-engaging portion having a workpiece-engaging surface;
said workpiece-engaging portion including a sandwich member mounted
on said bed;
sealing means for sealing said workpiece-engaging portion with said
workpiece, said sealing means including a first resilient member
arranged to seal between said workpiece-engaging surface and said
workpiece, wherein said workpiece, said sealing means and said
workpiece-engaging portion collectively form a first chamber;
vacuum supply means for supplying a vacuum to said first chamber to
draw together said workpiece and said workpiece-engaging portion;
and
pressure supply means for applying a pressure to said first
resilient member to force said first resilient member against said
workpiece and said workpiece-engaging portion
said sandwich member having a pair of opposite surfaces including a
workpiece-engaging surface and a bed-engaging surface, an aperture
formed in said sandwich member and extending between said
workpiece-engaging and said bed-engaging surfaces, wherein said
aperture has a periphery formed on both said workpiece-engaging and
said bed-engaging surfaces;
said first resilient member being arranged to seal between said
workpiece-engaging surface and said workpiece, said sealing means
further comprising a second resilient member arranged to seal
between said bed-engaging surface and said bed, wherein said
sealing means, said sandwich member, said bed and said workpiece
collectively form a first chamber;
said vacuum supply means being further arranged to supply a vacuum
to said first chamber to draw together said workpiece, said
sandwich member and said bed; and
said pressure supply means being further arranged to apply a
pressure to both said first and second resilient members to force
said first resilient member against said sandwich member and said
workpiece and to force said second resilient member against said
sandwich member and said bed.
20. A machine as defined in claim 19 wherein said sandwich member
further includes a first recess formed adjacent said periphery in
said workpiece-engaging surface and a second recess formed adjacent
said periphery in said bed-engaging surface, said first and second
resilient members being engaged with said first and second recesses
respectively, wherein said first and second resilient members and
said first and second recesses collectively form a second chamber,
said pressure supply means supplying pressure to said second
chamber.
21. A machine as defined in claim 20 wherein said first and second
resilient members are o-rings.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to workpiece processing machines and
more particularly to methods and devices for clamping workpieces
thereto.
2. Description of the Related Art
Workpiece processing machines such as milling machines are commonly
found in modern metal machining facilities. One type of milling
machine is a gantry type having a large workpiece receiving bed and
a tool driver positioned above the bed with three axes of
movement.
Commonly, the work piece is clamped to the bed by a number of
clamps bolted into selected locations on the bed. In some cases,
special fixtures are welded to the workpiece in order to use the
clamps. Either technique can be a complicated and time consuming
process. Yet, these clamping techniques remain as standards in
industry.
It is an object of the present invention to provide obviate or
mitigate these difficulties.
SUMMARY OF THE INVENTION
Briefly stated, the invention involves a device for clamping a
workpiece to a workpiece processing machine, the device
comprising;
a workpiece-engaging portion including a workpiece-engaging
surface;
sealing means for sealing the workpiece-engaging portion with the
workpiece; the sealing means including a first resilient member
arranged to seal between the workpiece-engaging surface and the
workpiece, wherein the sealing means, the workpiece-engaging
portion and the workpiece collectively form a first chamber;
vacuum supply means for supplying a vacuum to the first chamber to
draw together the workpiece and the workpiece-engaging portion;
and
pressure supply means for applying a pressure to the first
resilient member to force the first resilient member against the
workpiece-engaging portion and the workpiece.
In another aspect of the present invention, there is provided a
method for clamping a workpiece to a workpiece processing machine,
comprising the steps of:
providing a workpiece-engaging portion including a
workpiece-engaging surface;
locating a workpiece on the workpiece-engaging surface;
sealing the workpiece-engaging portion with the workpiece, the step
of sealing further including the step of providing a first
resilient member to seal between the workpiece-engaging surface and
the workpiece so that the workpiece-engaging portion and the
workpiece collectively form a first chamber;
providing a supply of vacuum to the first chamber to draw together
the workpiece and the workpiece-engaging portion; and
providing a supply of pressure to the first resilient member to
force the first resilient member against the workpiece-engaging
portion and the workpiece.
In still another aspect of the present invention, there is provided
a workpiece processing machine comprising;
a bed;
means for clamping a workpiece to the bed, including at least one
workpiece-engaging portion having a workpiece-engaging surface;
sealing means for sealing the workpiece-engaging portion with the
workpiece, the sealing means including a first resilient member
arranged to seal between the workpiece-engaging surface and the
workpiece, wherein the workpiece, the sealing means and the
workpiece-engaging portion collectively form a first chamber;
vacuum supply means for supplying a vacuum to the first chamber to
draw together the workpiece and the workpiece-engaging portion;
and
pressure supply means for applying a pressure to the first
resilient member to force the first resilient member against the
workpiece and the workpiece-engaging portion.
BRIEF DESCRIPTION OF THE DRAWINGS
Several preferred embodiments of the present invention will now be
described, by way of example only, with reference to the appended
drawings in which:
FIG. 1 is a perspective view of a gantry type milling machine;
FIG. 2 is a perspective view of a clamping device for the milling
machine of FIG. 1;
FIG. 3 is a side view of a portion of the device illustrated in
FIG. 2;
FIG. 3a is a sectional view of another portion of the device
illustrated in FIG. 2 in an operative position;
FIG. 4 is a side view of one element of the device illustrated in
FIG. 2;
FIG. 5 is a plan view of the element illustrated in FIG. 4;
FIG. 6 is a sectional view taken on line 6--6 of FIG. 5;
FIG. 7 is a sectional view taken on line 7--7 of FIG. 5;
FIG. 8 is a side view of a portion of another milling machine;
FIG. 9 is a side view of a portion of still another milling
machine; and
FIG. 10 is a side view of a portion of yet another milling
machine.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to the figures, there is provided a workpiece processing
machine in the form of a gantry type milling machine 10 having a
workpiece-receiving bed 12 and a tool driver 14 located above the
bed and operable with three axes of movement.
Referring to FIG. 2, there is provided a device 16 for clamping a
workpiece shown at 17 to the bed 12 of the milling machine 10. As
will be described, the device 16 includes a pair of sandwich
members 18. As shown in FIG. 3, each sandwich member 18 has a pair
of opposite surfaces including a workpiece-engaging surface 20 and
a bed-engaging surface 22. An aperture 24 is formed in the sandwich
member and extends between the workpiece-engaging and the
bed-engaging surfaces 20 and 22 respectively. The aperture is
further provided with a periphery shown at 24a.
A sealing means is provided for sealing the periphery 24a when the
workpiece-engaging and the bed-engaging surfaces are engaged with
the workpiece and bed respectively. In the embodiment shown in the
figures, this sealing means is in the form of a first resilient
member arranged to seal between the workpiece-engaging surface and
the workpiece and a second resilient member arranged to seal
between the bed-engaging surface and the bed. In this manner, the
sealing means, the sandwich member, the bed and the workpiece form
a first chamber.
Referring to FIG. 2, a supply means is also provided at 26 to
supply both a vacuum and a pressure to the device 16. The supply
means includes a vacuum supply 28 which is in fluid communication
with each of the first chambers by way of a number of vacuum lines,
one of which is shown at 30. As will be explained, the vacuum
supply is arranged to draw the workpiece, the sandwich member and
the bed together.
The supply means also includes a pressure supply 32 which is in
fluid communication with each of the first and second resilient
members by way of a number of pressure lines, one of which is shown
at 34. As will be explained, the pressure supply means is arranged
to apply a pressure to the first and second resilient members to
force the first resilient member against the sandwich member and
the workpiece and to force the second resilient member against the
sandwich member and the bed.
Referring more particularly to FIGS. 6 and 7, the sandwich member
further includes a first recess 36 formed adjacent the periphery
24a in the workpiece-engaging surface 20 and a second recess 38
formed adjacent the periphery 24a in the bed-engaging surface 22.
In this case, the first and second resilient members are in the
form of o-rings 40 and 42 respectively and each is engaged with a
respective recess 36 and 38. Furthermore, a passage 44 is formed
between the recesses 36 and 38 to join with the pressure line 34 to
form collectively a second chamber. More particularly, as shown in
FIG. 3a, the second chamber is formed by the recess 36 having an
inner surface portion 36a and an exposed outer surface 40a on the
resilient member which is exposed to the inner surface portion
36a.
The there should be a slight `squeeze` between the o-ring and the
recess allowing the second chamber to be sealed while permitting
the o-ring to travel outwardly under the influence of the pressure
to engage the workpiece or the bed as the case may be. For example,
a prototype of the present embodiment makes use of a recess having
a cross sectional width of 0.200 inches while each o-ring has a
diameter of 0.207 inches, giving a squeeze tolerance of 3.4
percent. This is contrasted with conventional o-ring squeezing
tolerances of up to 20 percent. In other words, the o-ring must be
able to move freely in the recess while be capable of sealing
against the walls thereof.
In use, the sandwich members are placed on the bed of the milling
machine, with the vacuum and pressure lines joined with the first
and second chambers respectively. The workpiece is then installed
on the sandwich members. It will be understood that, while only two
sandwich members are shown in the figures, any number of sandwich
members may be provided depending on the dimensions of both the
sandwich members and the workpiece. For example, three rows of two
sandwich members each may provide sufficient support beneath the
workpiece to prevent the workpiece from shifting during the milling
operation.
Once the workpiece is installed, the vacuum and pressure supplies
are activated drawing a vacuum inside the first chamber and a
establishing a pressure inside the second chamber. As the level of
vacuum increases in the first chamber (which for example may be at
a level of 10 pounds per square inch), the effective clamping force
of the workpiece correspondingly increases according to the cross
sectional area of the aperture multiplied by the pressure
deferential between the first chamber and ambient pressure.
The pressure supply pressurizes the second chamber which causes the
o-ring to be forced outwardly (for example at a pressure of 20
pounds per square inch). Had the workpiece not been in place, the
pressure supply would force the o-ring out of the recess. However,
with the workpiece in place, the o-ring is instead pressed against
the walls of the recess as well as the surface of workpiece to take
on an elliptical cross section as shown in FIG. 3a. In this manner,
the o-ring is forced to conform with irregularities on the surface
of the workpiece, such as mill-scale, a spot of weld, dirt and the
like. As a result, the o-ring is able to accommodate these
irregularities and enhance the seal at the periphery of the
aperture and thus the first chamber. In other words, the first
resilient member is movable in the recess under the action of the
pressure to establish a seal between the workpiece and the
resilient member, while maintaining a seal between the resilient
member and the recess.
Were it not for the pressure means, the first and second resilient
members may not be able to accommodate these irregularities on the
workpiece (and indeed those that may exist on the bed as well),
thus limiting the vacuum if any that can be established in the
first chamber and thus the clamping force of the workpiece.
If desired, the sandwich member may be equipped with just one
operable sealing surface, such as the one to receive the workpiece.
In this case, the other surface may lie against, but be otherwise
attached to, the bed of the milling machine as shown for example in
FIG. 8. In this case, the sandwich member 50 is fixed to the bed 52
by way of fasteners shown by the dashed lines at 54.
If desired, the workpiece-engaging portion may alternatively form
an integral part of the bed of the milling machine itself as shown
at 56 in FIG. 9.
While the above embodiments illustrate the use of an aperture and
the o-ring located adjacent the aperture, the device may provide
adequate clamping effect without the need of the aperture, apart
from that needed to establish the vacuum in the first chamber. For
example, FIG. 10 illustrates such a case where the first chamber 60
is formed in part by a concave surface on the workpiece shown in
dashed lines.
Although the above embodiments discuss a clamping technique used
with a milling machine, other types of workpiece processing
equipment may equally benefit from the clamping technique
disclosed, such as drilling, sawing and routing machines as well as
others that make use of a workpiece receiving bed.
* * * * *